[PATCH 2/2] qemu: support for virtio-blk-pci discard options

[yuxiating <yuxiating@xxxxxxxxxx>]

DISCARD and WRITE_ZEROES features for machine type >= 4.0 is enabled by default since
      commit 5c81161f804144b146607f890e84613a4cbad95c
      virtio-blk: add "discard" and "write-zeroes" properties
Sometimes guestos has bugs DISCARD need to be disabled.

Signed-off-by: yuxiating <yuxiating@xxxxxxxxxx>
---
 src/conf/domain_conf.c     | 15 +++++++++++++++
 src/conf/domain_conf.h     |  9 +++++++++
 src/conf/domain_validate.c |  6 ++++++
 src/libvirt_private.syms   |  3 ++-
 src/qemu/qemu_command.c    | 11 +++++++++++
 5 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 6127513117..bfe4721e60 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -1278,6 +1278,13 @@ VIR_ENUM_IMPL(virDomainDiskDiscard,
               "ignore",
 );
 
+VIR_ENUM_IMPL(virDomainDiskDiscardEnable,
+              VIR_DOMAIN_DISK_DISCARD_ENABLE_LAST,
+              "default",
+              "off",
+              "on",
+);
+
 VIR_ENUM_IMPL(virDomainDiskDetectZeroes,
               VIR_DOMAIN_DISK_DETECT_ZEROES_LAST,
               "default",
@@ -8930,6 +8937,10 @@ virDomainDiskDefDriverParseXML(virDomainDiskDef *def,
     if (virXMLPropUInt(cur, "queues", 10, VIR_XML_PROP_NONE, &def->queues) < 0)
         return -1;
 
+    if (virXMLPropEnum(cur, "discard_enable", virDomainDiskDiscardEnableTypeFromString,
+                       VIR_XML_PROP_NONZERO, &def->discard_enable) < 0)
+        return -1;
+
     return 0;
 }
 
@@ -23416,6 +23427,10 @@ virDomainDiskDefFormatDriver(virBuffer *buf,
     if (disk->queues)
         virBufferAsprintf(&attrBuf, " queues='%u'", disk->queues);
 
+    if (disk->discard_enable)
+        virBufferAsprintf(&attrBuf, " discard_enable='%s'",
+                          virDomainDiskDiscardEnableTypeToString(disk->discard_enable));
+
     virDomainVirtioOptionsFormat(&attrBuf, disk->virtio);
 
     if (disk->src->metadataCacheMaxSize > 0) {
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index c7e6df7981..c39694a19e 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -457,6 +457,13 @@ typedef enum {
     VIR_DOMAIN_DISK_DISCARD_LAST
 } virDomainDiskDiscard;
 
+typedef enum {
+    VIR_DOMAIN_DISK_DISCARD_ENABLE_DEFAULT = 0,
+    VIR_DOMAIN_DISK_DISCARD_ENABLE_OFF,
+    VIR_DOMAIN_DISK_DISCARD_ENABLE_ON,
+    VIR_DOMAIN_DISK_DISCARD_ENABLE_LAST
+} virDomainDiskDiscardEnable;
+
 typedef enum {
     VIR_DOMAIN_DISK_DETECT_ZEROES_DEFAULT = 0,
     VIR_DOMAIN_DISK_DETECT_ZEROES_OFF,
@@ -589,6 +596,7 @@ struct _virDomainDiskDef {
 
     bool diskElementAuth;
     bool diskElementEnc;
+    virDomainDiskDiscardEnable discard_enable;
 };
 
 
@@ -3838,6 +3846,7 @@ VIR_ENUM_DECL(virDomainDiskIo);
 VIR_ENUM_DECL(virDomainDeviceSGIO);
 VIR_ENUM_DECL(virDomainDiskTray);
 VIR_ENUM_DECL(virDomainDiskDiscard);
+VIR_ENUM_DECL(virDomainDiskDiscardEnable);
 VIR_ENUM_DECL(virDomainDiskDetectZeroes);
 VIR_ENUM_DECL(virDomainDiskModel);
 VIR_ENUM_DECL(virDomainDiskMirrorState);
diff --git a/src/conf/domain_validate.c b/src/conf/domain_validate.c
index 60f7ccdddd..6eb346916a 100644
--- a/src/conf/domain_validate.c
+++ b/src/conf/domain_validate.c
@@ -612,6 +612,12 @@ virDomainDiskDefValidate(const virDomainDef *def,
             return -1;
         }
 
+        if (disk->discard_enable) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("discard_enable attribute in disk driver element is only supported by virtio-blk"));
+            return -1;
+        }
+
         if (disk->event_idx != VIR_TRISTATE_SWITCH_ABSENT) {
             virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                            _("disk event_idx mode supported only for virtio bus"));
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index ab8a6c00c3..52a74dd2d5 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1,5 +1,5 @@
-#
 # General private symbols. Add symbols here, and see src/meson.build for
+# mainDiskDeviceTypeToString
 # more details.
 #
 # Keep this file sorted by header name, then by symbols with each header.
@@ -377,6 +377,7 @@ virDomainDiskDefParseSource;
 virDomainDiskDetectZeroesTypeFromString;
 virDomainDiskDetectZeroesTypeToString;
 virDomainDiskDeviceTypeToString;
+virDomainDiskDiscardEnableTypeToString;
 virDomainDiskDiscardTypeToString;
 virDomainDiskEmptySource;
 virDomainDiskErrorPolicyTypeFromString;
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index b230314f7f..894c8b17b9 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1739,6 +1739,17 @@ qemuBuildDiskDeviceStr(const virDomainDef *def,
             virBufferAsprintf(&opt, ",num-queues=%u", disk->queues);
         }
 
+        if (disk->discard_enable) {
+            if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_DISCARD)) {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                               _("virtio-blk discard property isn't supported by this "
+                                 "QEMU binary"));
+                return NULL;
+            }
+            virBufferAsprintf(&opt, ",discard=%s",
+                              virDomainDiskDiscardEnableTypeToString(disk->discard_enable));
+    }
+
         qemuBuildVirtioOptionsStr(&opt, disk->virtio);
 
         if (qemuBuildDeviceAddressStr(&opt, def, &disk->info) < 0)
-- 
2.27.0